1. Field of the Invention
The present invention relates to a method of supplying parts and to a supplying device, particularly to a waterproof plug supplying device for supplying waterproof plugs used mainly for a wiring harness of an automotive vehicle to a device for automatically attaching the supplied waterproof plug to an electric wire.
2. Description of the Prior Art
As the above waterproof plug supplying device, there have been disclosed parts feeders in which the waterproof plugs are aligned in a line along a conveyance path and are fed one after another to a transfer position located at the first in the line as shown in (1): FIG. 1 of Japanese Unexamined Patent Publication No. 2-75181, (2): FIG. 1 of Japanese Unexamined Patent Publication No. 2-75182, and (3): FIG. 6 of Japanese Unexamined Utility Model Publication No. 60-168286.
However, in the parts feeders disclosed in the above publications (1) to (3), the waterproof plugs aligned in a line are respectively fed by being pushed forward by the succeeding waterproof plugs. This has caused the following problems. The waterproof plug is normally made of rubber and a flash may remain in a parting line formed during the molding. There have been cases where the waterproof plugs fall forward on the conveyance path because the flash catches the inner wall of the conveyance path or the other waterproof plug or because of the vibration of the feeder itself. In this case, the fallen waterproof plugs may be conveyed to the transfer position or may cause a jam on the conveyance path. As a result, the waterproof plugs cannot be supplied properly.
In order to smoothly convey the waterproof plugs along the conveyance path, there has been proposed a parts feeder in which a guide rail is provided at the bottom surface of the conveyance path. The conveyance path and each waterproof plug is provided with a contact portion formed of synthetic resin such that it can be slidably guided by the guide rail (see the disclosure on left column, page 3 and FIGS. 1, 4 and 5 of Japanese Unexamined Patent Publication No. 5-77858 (Publication (4)). However, this parts feeder employs a design change with which the waterproof plug is comprised of a plurality of parts, making the structure thereof complicated. This has lead to an increased production cost.
Any one of the parts feeders disclosed in the publications (1) to (4) is adapted to the specification (shape and size) of the waterproof plugs, and there are 70 to 80 different specifications for the waterproof plugs. Thus, it was necessary to prepare a multitude of parts feeders. Further, when the specification of the waterproof plugs to be attached is changed, a parts feeder in the device for attaching the waterproof plugs to the electric wires must be entirely changed to the one suitable for the changed waterproof plugs. Thus, the replacement has taken a lot of cost and time. Particularly, in the production of the wiring harness, a wide variety of waterproof plugs have, in recent years, been produced each in a small quantity and the number of replacement has been exceedingly increased. Therefore, a long replacement time leads to a reduction in the projection efficiency.
It is an object of the invention to provide a method of supplying parts and a supplying device, particularly a waterproof plug supplying device, which are capable of securely supplying parts, particularly waterproof plugs without necessitating any design change in the parts and with which replacement can be easily made within a short period of time when the kind of the parts is changed.